How To Integrate GitLab With Jenkins

Before You Begin

In this tutorial, I’m going to demonstrate to you how to integrate GitLab with Jenkins Server. I suppose You’ve already installed Jenkins on your own. If you haven’t Jenkins server, Please refer to my previous video and article. I’ll put the link in the description.

REF: https://digitalavenue.dev/How-To-Install-and-configure-Jenkins-on-Ubuntu-18.04/

How To Install and Configure Jenkins : https://digitalave.github.io/spring/2020/04/06/How-To-Install-and-configure-Jenkins-on-Ubuntu-18.04.html

If you don’t have a GitLab account, Please create an account.

REF: https://gitlab.com/

Prerequisites :

• Pre-Configured Jenkins Server

• GitLab Account With Developer Role Permission

Introduction :

Jenkins is an open-source software development platform enriched with continuous integration (CI) and many more DevOps automation capabilities.

Organizations using Jenkins to build and deploy applications and integrate with GitLab for other DevOps tools.

GitLab - Jenkins integration allows you to build and deploy an application on Jenkins and reflect the output on the GitLab UI more convenience

Integration GitLab and Jenkins allows you to trigger a Jenkins build when a code is pushed to a repository or when a merge request is created.

STEP 01: Install GitLab Plugins on Jenkins Server

Go to the Manage Plugin section, then search and install the following plugins on your Jenkins server.

"Git"

"GitLab Plugin"

"GitLab API Plugin"

"Credentials Plugin"

"GitLab Authentication Plugin"

Manage Jenkins > Manage Plugins > Available Plugin [Search] > Install and Restart

STEP 02: Create a New GitLab User / Promote Existing GitLab User

Create a new GitLab user with “Developer” role permission and grant access to each repository/project you want to integrate with Jenkins

Note: User should have Developer Permission Role

STEP 03: Create Personal Access Token on GitLab

Now, Let’s head over to the GitLab account and move to your profile setting section.

User Settings > Access Tokens

Create a new Personal Access Token for Jenkins authentication.

Name: Provide Token Name

Scope: API - Which Grant access to GitLab resources such a Projects, Groups and Registries.

Save the deployed token somewhere safe. Once you leave or refresh the page, you won’t be able to reaccess it.

NOTE: Once you’ve generated a Personal Access Token, copy it and save it in a separate file immediately.Because Token only visible only once.

Jenkins-GitLAB_API-Access : i5Jfi8a5foEFoC9CkVzl

STEP 04: Add GitLab Personal Access Token to Jenkins

Again, Head-over to the Jenkins server and Then, We need to add an authentication token into the Jenkins server.

Jenkins > Credentials > System > Global Credentials > Add Credentials

Scroll down a little and click on “Global Credentials” under the Domain column and “Add Credentials”.

Select the following options for the “Global Credentials” section.

Kind: GitLab API Token

API Token: Add Previously Generated Personal Access Token

Description: Provide a Descriptive Name

STEP 05: Configure GitLab API Settings on Jenkins Server

Let’s move on to “GitLab” configuration section in Manage Jenkins > Configure System.

Manage Jenkins > Configure System > “GitLAB” Configuration Section.

Then, Configure the following entries…

Enable authentication for ‘/project’ end-point : Enable

Connection Name: Provide a Descriptive Name

GitLab host URL: GitLab server URL

Credentials: Select previously added credentials from the drop-down menu.

Finally, check whether the connection is successful by pressing “Test Connection” button. If the connection is successful. Then move to the next step.

Now, the Connection between Jenkins and GitLab is OK. GitLab API plugin used to access for Jenkins to get metadata from GitLab.

But, We need to have an SSH key authentication to commit changes from Jenkins to GitLab.

STEP 06: Allow GitLab Build Commit Push-Pull Authentication To GitLab

Two Methods :

1. Using SSH public-Private Key Pair

Create SSH Key Pair on Jenkins Server

Login to Jenkins host terminal console and switch to “jenkins” user and move to Jenkins home directory. And generate an SSH-Key-Pair.

root@SRV3:~# su - jenkins
jenkins@SRV3:~$ cd /var/lib/jenkins/
jenkins@SRV3:~$ ssh-keygen 
Generating public/private rsa key pair.
jenkins@SRV3:~$ cd /var/lib/jenkins/.ssh/
jenkins@SRV3:~/.ssh$ ls
id_rsa  id_rsa.pub  known_hosts

Open “id_rsa.pub” file and copy the content.

Provide Public Key To GitLab

Go to GitLab and deploy a new ssh key. Go to your GitLab profile “Setting” and then go to “SSH Keys” section.

Paste code that we copied content from “id_rsa.pub” file.

Now, a Public key has been added to the GitLab server.

Provide Private Key To Jenkins

Then, We need to add our private key to the Jenkins server.

Open “/var/lib/jenkins/.ssh/id_rsa” file and copy content from private key.

vim /var/lib/jenkins/.ssh/id_rsa

Go to Jenkins > Credentials > System > Global Credentials > Add Credentials

Click the “Add” button next to the “Credentials” field and select the “Jenkins” option. In the resulting dialogue, select “SSH Username with private key” as the credential typeset the “Username” to git, and enter the content of the private key selected for use between GitLab and Jenkins.

Kind: SSH Username with private key

Description: Provide descriptive name

** Username: git**

Private Key: Enter private key

Remember that you already attached the corresponding public key to your GitLab profile in step in the previous step.

Add copied public key content into “Key” section.

2. Using Plain Credentials - Username:Password

STEP 07: Push Local Project To GitLab - Optional Step

Now, I’m going to push my local project into the GitLab repository.

Open Your Command Prompts / Or Use Your Own Method

C:\Users\Dimuthu>git config --global user.name "Dimuthu Daundasekara"

C:\Users\Dimuthu>git config --global user.email "dimuthu@gmail.com"

C:\Users\Dimuthu>cd C:\YoutubeDownloader-master\YoutubeDownloader

C:\YoutubeDownloader-master\YoutubeDownloader>git init

C:\YoutubeDownloader-master\YoutubeDownloader>git remote add origin git@gitlab.com:dimuit86/youtubedownloader.git

C:\YoutubeDownloader>git add .

C:\YoutubeDownloader-master\YoutubeDownloader>git commit -m "Initial commit"

C:\YoutubeDownloader>git config credential.helper store

C:\YoutubeDownloader-master\YoutubeDownloader>git push https://gitlab.com/dimuit86/youtubedownloader.git

STEP 07: Configure Jenkins Project

Create FreeStyle Project on Jenkins

Now, It’s time to create a new project and do further configuration.

Jenkins > New Item > FreeStyle Project

Give a name to the project and continue.

Now, Head-over to the “source code management” section and select “Git”.

Repository URL : git@gitlab.com :dimuit86/shadowsocksx-ng-develop.git

Credentials: Select added credentials from drop-down menu

Attach new credentials to the SSH URL for the GitLab repository.

Optional: You also can use the plain Username and password that we have added to the method (2).

On the same configuration page, find the “Build Triggers” section and check the option to “Build when a change is pushed to GitLab”.

Finally, Apply and Save Changes

Now, GitLab integration with Jenkins has been completed. Now, We can check the connectivity, using the build button and checking console logs.

Voilà, It’s working.